This invention relates to an automatic control device for filters to correct the spectral characteristic of illuminating lights in response to the color temperature thereof and the presence of flickers.
It is conventional practice to place a correcting filter on a camera lens when the lighting conditions are different from the lighting conditions for which the loaded film is designed. Several automatic means for selecting the proper correcting filter are known in the art. Examples are disclosed in Japanese Pat. Publication No. 26700/1968, No. 27576/1968 and No. 14431/1971. Such devices are designed to select the correcting filter in response only to the color temperatures of the illuminating light. However, since the light from a fluorescent lamp has a color temperature comparatively similar to that of ordinary sunlight, it is extremely difficult to discriminate sunlight from fluorescent lamp light only by differentiating their respective color temperatures. Consequently most photographic images obtained under fluorescent lighting conditions tend to be green even if a colored negative film or reversal film is used.